1. Field of the Invention
The present invention relates to a method for enabling a file, which is stored on a storage medium together with at least one other file, for use by a single computer system or by a limited number of local computer systems. The invention also relates to a system for managing and enabling use rights on files.
2. Description of the Related Art
Computer programs and databases are usually sold to the end user on a storage medium, such as a CD-ROM. Such a storage medium has a high storage capacity and can usually hold a number of computer programs, possibly in compressed form. Such a CD-ROM can therefore have a high selling value. Using suitable devices (“CD burners”), it is a relatively simple matter to make copies of CD-ROMs. Copied CD-ROMs are sometimes swapped free of charge among interested parties or are sold illegally. There is therefore a need to enable appropriate programs or, more generally, files only for registered users.
Since a single CD-ROM can hold a number of programs or files, it is also important to enable only individual programs or a particular number of programs for a particular user. By way of example, a CD-ROM can hold the usual standard office software. Office software includes, by way of example, a word-processing program, a spreadsheet, a database program and a program for creating presentations. However, the individual user is sometimes interested only in some of the programs, such as the word-processing program and the spreadsheet, while the other components are not important to him. The case may also arise in which a user is interested only in the updated version of one of these programs, but otherwise the older versions of the rest of the programs are entirely adequate for him, because he uses them only rarely, for example. Nevertheless, in both cases, the user occasionally has to purchase the entire package because the individual programs are not available separately. This is because selling the programs individually requires greater effort from the manufacturer, and is therefore frequently not done. For the cases mentioned, it is therefore useful to enable only individual programs or files on a CD-ROM for use by a particular user. Ideally, such enabling should again be associated with an appropriate level of copy protection, so that, once the file has been enabled, it can also be used only by the registered and authorized user.
EP 0 679 979 A1 discloses a method which is used to allocate temporary use rights on a piece of computer software. To this end, the encrypted software is first stored on a storage medium together with a file management program. The storage medium is then sent to the potential user. The user then loads the file management program into his computer system. The program stored on the storage medium is then accessible for this computer system. The file management program loaded into the computer restricts access to the program. Although the method described can be used to ensure restricted access to a computer program, there is no provision for just individual files or programs to be enabled specifically.
It is therefore one object of the present invention to specify a method which, first, ensures that a computer program or a file is used only by an authorized user, and, second, allows just individual programs or files on a storage medium to be enabled for a particular user.
It is another object of the present invention to specify a system for managing and enabling use rights on files which can be used to carry out such a method. Other objects and advantages of the present invention will be apparent in light of the following Summary and Detailed Description of the presently preferred embodiments.